The prevalence of HBV and HCV infection among 295 cholangiocarcinoma (CCA) patients in northeast Thailand was analyzed. Hepatitis B surface antigen (HBsAg) was detected in 8.8% (26/295 cases) and antibodies to HCV (anti-HCV) in 2.7% (8/295 cases) of CCA cases. Screening for HBV DNA was performed in 15 of 26 HBV seropositive cases and genotypes could be determined in all 15. HBV genotypes C and B were detected in 73.3% (11/15 cases) and 26.7% (4/15 cases), respectively. HCV RNA was detected in 87.5% (7/8 cases) of anti-HCV positive cases. Specifically, 57.1% (4/7 cases) were HCV genotype 1a and 42.9% (3/7 cases) were HCV genotype 3a. The prevalence of infection and genotype distribution of both HCV and HBV among CCA in northeast Thailand is comparable to that in the general population, suggesting that HCV and HBV infections are, if at all, not serious risk factors for CCA.